Application of Bacteriorhodopsin Films in an Adaptive-Focusing Schlieren System

The photochromic property of bacteriorhodopsin films is exploited in the application of a focusing schlieren optical system for the visualization of optical phase information. By encoding an image on the film with light of one wavelength and reading out with a different wavelength, the readout beam can effectively see the photographic negative of the original image. The potential advantage of this system over previous focusing schlieren systems is that the updatable nature of the bacteriorhodopsin film allows system adaptation. I discuss two image encoding and readout techniques for the bacteriorhodopsin and use film transmission characteristics to choose the more appropriate method. I demonstrate the system principle with experimental results using argon-ion and He-Cd lasers as the two light sources of different wavelengths, and I discuss current limitations to implementation with a white-light source

Nonlinear Coherent Optical Image Processing Using Logarithmic Transmittance of Bacteriorhodopsin Films

The transmission properties of some bacteriorhodopsin-film spatial light modulators are uniquely suited to allow nonlinear optical image-processing operations to be applied to images with multiplicative noise characteristics. A logarithmic amplitude-transmission characteristic of the film permits the conversion of multiplicative noise to additive noise, which may then be linearly filtered out in the Fourier plane of the transformed image. I present experimental results demonstrating the principle and the capability for several different image and noise situations, including deterministic noise and speckle. The bacteriorhodopsin film studied here displays the logarithmic transmission response for write intensities spanning a dynamic range greater than 2 orders of magnitude

Optical Logarithmic Transformation of Speckle Images with Bacteriorhodopsin Films

The application of logarithmic transformations to speckle images is sometimes desirable in converting the speckle noise distribution into an additive, constant-variance noise distribution. The optical transmission properties of some bacteriorhodopsin films are well suited to implement such a transformation optically in a parallel fashion. I present experimental results of the optical conversion of a speckle image into a transformed image with signal-independent noise statistics, using the real-time photochromic properties of bacteriorhodopsin. The original and transformed noise statistics are confirmed by histogram analysis

Optical Correlation of Images With Signal-Dependent Noise Using Constrained-Modulation Filter Devices

Images with signal-dependent noise present challenges beyond those of images with additive white or colored signal-independent noise in terms of designing the optimal 4-f correlation filter that maximizes correlation-peak signal-to-noise ratio, or combinations of correlation-peak metrics. Determining the proper design becomes more difficult when the filter is to be implemented on a constrained-modulation spatial light modulator device. The design issues involved for updatable optical filters for images with signal-dependent film-grain noise and speckle noise are examined. It is shown that although design of the optimal linear filter in the Fourier domain is impossible for images with signal-dependent noise, proper nonlinear preprocessing of the images allows the application of previously developed design rules for optimal filters to be implemented on constrained-modulation devices. Thus the nonlinear preprocessing becomes necessary for correlation in optical systems with current spatial light modulator technology. These results are illustrated with computer simulations of images with signal-dependent noise correlated with binary-phase-only filters and ternary-phase-amplitude filters

G20 2014: the G20 Brisbane Summit, inequality, energy and anti-corruption

The 12th edition of the G20 monitor contains an overview from John Lipsky on the G20’s role in global governance after the global financial crisis; a paper by Geoff Weir on the G20, Thomas Piketty, and inequality; thoughts from Hugh Jorgensen and Christian Downie on multilateral energy governance; and a piece by Charles Sampford on integrity and anti-corruption. Key findings Lipsky suggests the Brisbane Summit is a critical moment for the G20, if it does not restore a sense of political momentum to the process, the G20’s relevance will wane Ever-growing inequality is inconsistent with the maintenance of an inclusive, democratic system of governance. The G20 should consider a combination of taxation, education and health reforms to reduce inequality. The world needs better multilateral energy governance. Whether the conditions exist for the G20 to remedy this problem is unclear, but members should pursue energy governance mechanisms that promote trust

The times are they a-changing? Evolving attitudes in Australian exercise science students’ attitudes towards sports concussion

The issue of concussion in sport continues to be discussed widely in the community as current and retired players reveal personal experiences, and concerns, about the long-term sequelae of their concussive injuries. This is the first study to examine evolving attitudes and beliefs towards concussion in sport by comparing data in an Australian exercise science student cohort between 2015 and 2020. Using a repeated cross-sectional design 1,013 participants (2020 cohort: n = 751; 21.6 ± 7.1 years; 2015 cohort: n = 312; 22.0 ± 5.2 years) responded to statements about concussion: personal attitudes; the media’s portrayal; elite athletes who continue to play concussed; if participants would continue to play on concussed; and on completing rehabilitation for concussion. Comparisons revealed statistically significant differences between cohorts across the majority of statements. Specifically, more progressive attitudes were found regarding the media presentation (glorification) of concussed athletes (decreased agreement of 14.7%, p < 0.001), admiration of concussed athletes who continued to play (decreased agreement of 10.5%, p < 0.001), and rehabilitation (increased agreement of 13%, p < 0.001). However, participants still presented attitudes of wishing to continue to train or play if they had a concussion for fear of letting team-mates down, or if the injury was not noticeable. While positive attitudes are evolving, more work is required, particularly as attitudes towards concussion still appear to be situation dependent

Tiotropium in asthmatic adolescents symptomatic despite inhaled corticosteroids: A randomised dose-ranging study

SummaryIntroductionTiotropium, a once-daily long-acting anticholinergic agent, has been shown to be an efficacious and safe add-on treatment for adults with symptomatic asthma, despite treatment with inhaled corticosteroids (ICS). A large proportion of asthmatic adolescents have symptomatic disease despite a wide range of therapeutic options. We investigated the efficacy and safety of three doses of tiotropium, administered in the evening (via Respimat® SoftMist™ inhaler), versus placebo in asthmatic adolescents symptomatic despite ICS treatment.MethodsThis randomised, double-blind, placebo-controlled, incomplete crossover study evaluated once-daily tiotropium 5 μg, 2.5 μg and 1.25 μg versus placebo in three 4-week treatment periods. Primary efficacy end point was change in peak forced expiratory volume in 1 s within 3 h post-dose from baseline (peak FEV1(0–3h)).ResultsFrom 139 enrolled patients, 105 were randomised to receive one of four treatment sequences. Peak FEV1(0–3h) response for tiotropium 5 μg was significantly greater versus placebo (p = 0.0043). Trough FEV1 responses were significantly greater for tiotropium 5 μg (p < 0.00001) and 1.25 μg (p = 0.0134) versus placebo, but not for 2.5 μg (p = 0.0975), while FEV1 area under the curve(0–3h) responses were significant for all doses (p = 0.00001–0.0398). Overall incidence of adverse events was balanced across treatment groups, with no dose-dependent observations. The majority of adverse events were mild to moderate in intensity.ConclusionThis first study of tiotropium in adolescents with symptomatic asthma demonstrates that tiotropium is well tolerated and efficacious as add-on to maintenance treatment with ICS.ClinicalTrials.gov identifier; NCT01122680